60 research outputs found
Pressure Study of BiS2-Based Superconductors Bi4O4S3 and La(O,F)BiS2
We report the electrical resistivity measurements under pressure for the
recently discovered BiS2-based layered superconductors Bi4O4S3 and La(O,F)BiS2.
In Bi4O4S3, the transition temperature Tc decreases monotonically without a
distinct change in the metallic behavior in the normal state. In La(O,F)BiS2,
on the other hand, Tc initially increases with increasing pressure and then
decreases above ? 1 GPa. The semiconducting behavior in the normal state is
suppressed markedly and monotonically, whereas the evolution of Tc is
nonlinear. The strong suppression of the semiconducting behavior without doping
in La(O,F)BiS2 suggests that the Fermi surface is located in the vicinity of
some instability. In the present study, we elucidate that the superconductivity
in the BiS2 layer favors the Fermi surface at the boundary between the
semiconducting and metallic behaviors.Comment: 4 pages, 6 figures, Accepted for publication in J. Phys. Soc. Jp
Fabrication of binary FeSe superconducting wires by novel diffusion process
We report successful fabrication of multi- and mono-core FeSe wires with high
transport critical current density Jc using a simple in-situ Fe-diffusion
process based on the powder-in-tube (Fe-diffusion PIT) method. The seven-core
wire showed transport Jc of as high as 1027 A/cm2 at 4.2 K. The superconducting
transition temperature Tczero was observed at 10.5 K in the wire-samples, which
is about 2 K higher than that of bulk FeSe. The Fe-diffusion PIT method is
suitable for fabricating multi-core wires of the binary FeSe superconductors
with superior properties.Comment: 14 pages, 5 figure
Superconductivity in oxygen-annealed FeTe1-xSx single crystal
We investigated the S-doping-driven phase transition from antiferromagnetic
to superconducting in FeTe1-xSx single crystals. The partial substitution of Te
by S suppresses antiferromagnetism in Fe-square lattice. Superconductivity is
induced by oxygen annealing for only FeTe1-xSx in which the long-range magnetic
ordering is suppressed. To realize superconductivity in FeTe1-xSx, both S
concentration enough to suppress antiferromagnetism and oxygen annealing are
required. Anisotropy of superconductivity in oxygen-annealed FeTe0.886S0.114
was estimated to be 1.17.Comment: 14 pages, 7 figure
- …